I get this error when I try to convert an wmv to 3gp using this command:

ffmpeg -y -i "inputvid.wmv" -vf scale=352:288 

       -f 3gp -vcodec h263 -r 15 -b:v 200k 

       -acodec libvo_aacenc -ac 2 -ar 32000 -b:v 64k 

       "outputvid.3gp"

(The command is actually derived from Mobile Media Converter 1.8.2 which recently fails on each conversion and I'm trying to troubleshoot.)

I have made the latest stable ffmpeg (version 0.10.8-7:0.10.8-1~raring1) using these instruction.

I appreciate your hints to either install libvo_aacenc, or some other codec to make conversion possible.